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A244193 Numbers n such that the difference between the greatest prime divisor of n and the sum of the other distinct prime divisors is equal to +-1. 1
6, 12, 18, 24, 36, 48, 54, 72, 96, 105, 108, 144, 162, 192, 216, 231, 288, 315, 324, 330, 384, 385, 429, 432, 455, 462, 486, 525, 546, 576, 648, 660, 663, 693, 735, 768, 864, 910, 924, 935, 945, 969, 972, 990, 1092, 1105, 1122, 1152, 1235, 1287, 1296, 1309 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence A215142 is included in this sequence.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

105 is in the sequence because 105 = 3*5*7 and 7 - (3 + 5) = 7 - 8 = -1;

231 is in the sequence because 231 = 3 * 7 * 11 and 11 - (3 + 7) = 11 - 10 = 1.

MAPLE

filter:= proc(n) local P, pmax;

     P:= numtheory[factorset](n);

     abs(convert(P, `+`)-2*max(P))=1

end proc;

select(filter, [$1..10000]); # Robert Israel, Jun 23 2014

MATHEMATICA

fpdQ[n_]:=Module[{f=Transpose[FactorInteger[n]][[1]]}, Max[f]-Total[Most[f]]==1]; gpdQ[n_]:=Module[{g=Transpose[FactorInteger[n]][[1]]}, Max[g]-Total[Most[g]]==-1]; Union[Select[Range[2, 3000], fpdQ ], Select[Range[2, 3000], gpdQ ]]

dbgQ[n_]:=Module[{fi=FactorInteger[n][[All, 1]]}, Abs[fi[[-1]]-Total[ Most[ fi]]]==1]; Select[Range[2, 1500], dbgQ] (* Harvey P. Dale, Jan 01 2020 *)

CROSSREFS

Cf. A033845, A215142.

Sequence in context: A189781 A182302 A353530 * A329878 A215142 A033845

Adjacent sequences:  A244190 A244191 A244192 * A244194 A244195 A244196

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jun 22 2014

STATUS

approved

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Last modified October 5 05:10 EDT 2022. Contains 357252 sequences. (Running on oeis4.)